TOXICITY OF FRESH AND FREEZE-DRIED HYDROCARBON-POLLUTED SEDIMENTS TO CRASSOSTREA-GIGAS EMBRYOS

Sediments from a known hydrocarbon-polluted site were stored fresh and freeze-dried, and subsequently used in liquid and suspended phase bioassays with Crassostrea gigas (Thunberg) oyster embryos. Fresh sediments did not affect embryogenesis while freeze-dried sediments stopped embryogenesis in the morula stage at 500 g I-1 and in the trocophore stage at 50 g I-1. At 5 g I-1, freeze-dried sediments were innocuous in the liquid phase bioassay (elutriate filtered through 0.45 mum) but appeared to reduce embryogenesis success in the suspended phase bioassay. The need for further research into the effects of the storage conditions and preservation methods of the sediment samples on the fate of the associated pollutants is demonstrated.